1. Field of the Invention
This invention relates to security devices, and particularly to an alarm system which may be physically attached to an object which it is desired to protect. If the physical integrity of the alarm system or its attaching means is compromised, an audible alarm will sound.
2. Description of the Prior Art
Alarm systems and anti-theft devices are known in the art. In general, such devices contain sensors to detect motion or a breach of integrity in the device itself or in the object being protected. The increase in sales and installation of home security systems and motor vehicle security systems is symptomatic of a society where the need for such security devices is increasing, and this need has resulted in an large number of such devices, many of which are unnecessarily expensive and complex.
There is a continuing need for simple and inexpensive security devices which can be used as an alarm when an object is disturbed or moved. Such a device is useful in many application ranging from securing a bicycle to a post or tree, to securing a cabinet door from access by a child, or sounding an alarm if a suitcase is taken from one's grasp.
There are a number of devices in the prior art that are useful for one or more of the applications listed. For example, U.S. Pat. No. 4,804,943 to Soleimani shows an alarm system for a briefcase which incorporates a radio receiver actuable by a transmitted signal to either sound an alarm or to separate the handle from the briefcase. This is one of many such security devices for briefcase which in general cause actuation of an alarm when the briefcase is removed from the grip of the authorized courier.
A device more similar to the present invention is shown in U.S. Pat. No. 4,833,456 to Heller. A motion sensor has attached thereto a conductive cable or tether which is secured around a portable object to be protected, typically a pair of skis. If continuous motion is sensed, or if the cable is disconnected, an alarm contained within the motion sensor will be activated. The device of the present invention does not rely on motion sensing, primarily because a motion sensor will often provide a false alarm if the property being protected or the security device are accidently moved.
Another security system, shown in U.S. Pat. No. 4,893,692 to Wolk et al, protects against the kidnapping of infants, but also has other applications. An rf transmitter is attached to the infant, and a receiver containing an alarm will be activated if the infant is removed from the vicinity of the receiver. In another embodiment the alarm is sounded if it is attempted to remove the transmitter from the infant.